<p>Thirty isolates of <i>Rhizoctonia solani</i> collected from various rice varieties grown in different regions of Andhra Pradesh were studied for their cultural, pathogenic and molecular variability. Many of the isolates were moderate growers while ten were fast growers. Colony color varied from white to brown. Hyphal width varied from 13.59 to 31.66&#xa0;μm. The color of sclerotia was initially white and dark brown with maturity. While sclerotia number ranged between 3 and 89 with different patterns, their size varied between 0.8 and 2.8&#xa0;mm. The virulence of each pathogen isolate was studied on three rice varieties, that is NLR-34449 (susceptible), IR-64 (moderately susceptible), Tetep (moderately resistant) in glasshouse, and observations were recorded by measuring the relative lesion height. The relative lesion heights of these isolates on three rice varieties varied widely based on which the isolates could be grouped as highly virulent, moderately virulent and less virulent. The RLH on NLR-34449 ranged from the lowest 15.13% to the highest 54.66%, on IR- 64 from the lowest 5.73% to the highest 49.03% and Tetep from the lowest 2.00% to the highest 38.46% by the isolates EAD (lowest) and WAK (highest), respectively. There was no relationship between culturally similar isolates and their pathogenic behavior. Genetic variation of the isolates was analyzed using RAPD markers. The primers OPA-07, OPA-10, OPC-11, OPC-19, OPB-17, OPE-06, OPF-14 and OPG-11were informative and given polymorphism among the isolates. The PIC (Polymorphic Information Content) values ranged from 0.36 (OPC-11) to 0.49 (OPG-11) with an average PIC value of 0.44. Largely, grouping of the isolates happened based on their geographical origin.</p>

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Cultural, pathogenic and genetic variability of Rhizoctonia solani isolates incitant of rice sheath blight disease

  • Y. Sandhya,
  • M. Reddi Kumar,
  • P. Madhusudhan,
  • P. Sudhakar,
  • P. Lavanya Kumari

摘要

Thirty isolates of Rhizoctonia solani collected from various rice varieties grown in different regions of Andhra Pradesh were studied for their cultural, pathogenic and molecular variability. Many of the isolates were moderate growers while ten were fast growers. Colony color varied from white to brown. Hyphal width varied from 13.59 to 31.66 μm. The color of sclerotia was initially white and dark brown with maturity. While sclerotia number ranged between 3 and 89 with different patterns, their size varied between 0.8 and 2.8 mm. The virulence of each pathogen isolate was studied on three rice varieties, that is NLR-34449 (susceptible), IR-64 (moderately susceptible), Tetep (moderately resistant) in glasshouse, and observations were recorded by measuring the relative lesion height. The relative lesion heights of these isolates on three rice varieties varied widely based on which the isolates could be grouped as highly virulent, moderately virulent and less virulent. The RLH on NLR-34449 ranged from the lowest 15.13% to the highest 54.66%, on IR- 64 from the lowest 5.73% to the highest 49.03% and Tetep from the lowest 2.00% to the highest 38.46% by the isolates EAD (lowest) and WAK (highest), respectively. There was no relationship between culturally similar isolates and their pathogenic behavior. Genetic variation of the isolates was analyzed using RAPD markers. The primers OPA-07, OPA-10, OPC-11, OPC-19, OPB-17, OPE-06, OPF-14 and OPG-11were informative and given polymorphism among the isolates. The PIC (Polymorphic Information Content) values ranged from 0.36 (OPC-11) to 0.49 (OPG-11) with an average PIC value of 0.44. Largely, grouping of the isolates happened based on their geographical origin.